Cell Organelles: Structure, Function, and Energy Production
Essential Cellular Organelles: Structure and Function
Membrane-Bound Organelles
Golgi Apparatus
The Golgi apparatus consists of flattened sacs (cisternae) and independent vesicles surrounded by a membrane and assembled in groups called dictyosomes. Its function is the secretion of substances taken from the endoplasmic reticulum and destined for lysosomes.
Lysosomes
Lysosome Structure and Role: These are spherical vesicles surrounded by a membrane, which contain hydrolytic enzymes. They are responsible for the digestion of complex substances, transforming them into simpler ones that can cross the membrane into the cytoplasm and are essential for use.
Vacuoles
Vacuoles are membrane-bound vesicles that originate in the endoplasmic reticulum or the Golgi apparatus. They are much more developed in plant cells. Their primary function is the storage of substances of different natures.
Energy Organelles
Mitochondria
Mitochondria are ovoid organelles surrounded by two membranes. The internal membrane issues a series of folds or ridges inwards (cristae) into the mitochondrial matrix, which contains its own genetic material, ribosomes, and enzymes. They perform cellular respiration to provide energy to the cell.
Chloroplasts
Chloroplasts are ellipsoid organelles made of a double membrane. They host a series of vesicles called thylakoids that contain the chlorophyll, which gives them their characteristic green color. The thylakoids are grouped into grana embedded in the matrix or stroma. Their function is the synthesis and accumulation of different substances; they perform photosynthesis. (Note: Chloroplasts are essential for photosynthesis, correcting the original text’s error.)
Non-Membranous Structures
Ribosomes
Ribosomes are granules composed of RNA and proteins, composed of two subunits. They perform protein synthesis.
Centrosome
The centrosome is formed by a pair of centrioles made of protein tubules. Centrioles are the start of filaments called the aster. The centrosome organizes the cytoskeleton and leads to the cilia or flagella (organelles for movement). It also acts in cell division.
Review: Key Organelle Structures and Functions
This section reiterates the essential information regarding cellular components, ensuring all original content is retained.
Golgi Apparatus
The Golgi apparatus consists of flattened sacs and independent vesicles assembled in groups or dictyosomes. Function: Secretion of substances taken from the endoplasmic reticulum and lysosomes.
Lysosomes
Structure: Spherical vesicles surrounded by a membrane, containing hydrolytic enzymes. Function: Digestion of complex substances into simpler ones essential for use in the cytoplasm.
Vacuoles
Membrane-bound vesicles originating in the endoplasmic reticulum or the Golgi apparatus. They are much more developed in plant cells. Function: Storage of substances of different natures.
Energy Organelles
Mitochondria
Ovoid organelles surrounded by two membranes. The internal membrane forms folds or ridges inwards into the mitochondrial matrix, containing genetic material, ribosomes, and enzymes. Function: Perform cellular respiration to provide energy to the cell.
Chloroplasts
Ellipsoid organelles made of a double membrane. They host thylakoids containing chlorophyll, grouped into grana embedded in the stroma. Function: Synthesis and accumulation of different substances; they perform photosynthesis.
Ribosomes
Granules composed of RNA and proteins, composed of two subunits. Function: Perform protein synthesis.
Centrosome
Formed by a pair of centrioles made of protein tubules. Centrioles start of filaments called the aster. Function: Organizes the cytoskeleton, leads to cilia or flagella, and acts in cell division.